1. Field of the Invention
The present invention relates to papermaking methods and apparatus. More specifically, the present invention relates to manual or hand methods of molding individual paper sheets with bench top mounted static apparatus.
2. Description of the Prior Art
One of the original processes by which paper has been made included the step of manually screen molding a "handsheet" whereby a dilute aqueous slurry of cellulose fiber was deposited on a sheet sized screen. As the slurry deposit occurred, water drained through the screen pores while the fibers randomly matted on the screen surface. Following the fiber matting, the freshly laid web, still in adherence to the screen, is layered between two absorbent material laminae and pressed. Thereafter, the pressed mat, now a consolidated sheet, may be peeled from the screen and further dried.
There are numerous examples of prior art apparatus for practicing the aforedescribed handsheet making process. However, U.S. Pat. No. 1,995,586 is representative of such prior art as it is relevant to the invention. By productivity comparison to the modern, machine driven screen technique of paper web molding, the individual handsheet molding technique is slow and laborious. Nevertheless, due to the simplicity of necessary tools and equipment, the handsheet technique of papermaking prevails: predominantly in the laboratories of pulp and papermakers for the purpose of pulp evaluation.
The relative strengths and drainage characteristics between two pulp blends may be comparatively measured from handsheets molded from the respective blends. However, heretofore it has been very difficult to directly translate such handsheet measurements to machine laid paper due to the relative difference in fiber orientation. Sheets made from the prior art handsheet technique have a completely random fiber direction orientation. Consequently, the sheet has equal tensile and tear strengths in all directions.
When a paper web is formed on a papermachine, the slurry is deposited on a closed loop screen (fourdrinier). As the screen is driven around the loop, the slurry flows from a slice jet onto the screen codirectionally with the screen travel and highly tangential therewith. The elongated fibers align themselves with the flow stream direction (machine direction; MD) and are deposited on the traveling screen accordingly. Since this fiber oriented aqueous slurry on the traveling screen is quickly consolidated to a mat, little opportunity is allowed for the flow aligned fibers to gain a random disposition. Consequently, the tensile strength of machine laid paper is considerably greater along the MD than along the CD (cross direction; transverse of flow stream direction).
Since the advent of the fourdrinier paper machine, there has been a need for a laboratory scale technique and/or apparatus to simulate, in a handsheet, the fiber orientation distribution of a fourdrinier pulp deposition. To the degree that this need has been satisfied, it has been with scale model fourdrinier machines. However, such a model for producing a mere 6 inch wide web is still, in absolutes a large, complicated and costly apparatus.
It is, therefore, an object of the present disclosure to teach a method and apparatus for molding paper handsheets having a directionally oriented fiber distribution.
Another object of the present invention is to simulate the fiber distribution pattern of a fourdrinier machine, with mechanically static, bench-top equipment.